Giant, invasive Joro spiders reappear across US states, experts say they're harmless

Giant, invasive Joro spiders are reappearing across multiple U.S. states, but experts assure the public they pose no threat. First detected in Georgia in 2014, these spiders, native to East Asia, have since been spotted in more than a dozen states, primarily in the Southeast.

Adult female Joro spiders are striking with their yellow bodies, bluish-green stripes, and black and yellow legs. They can reach up to 1 inch in body length with a leg span of up to 4 inches. Males are smaller and predominantly brown. While they possess the ability to 'balloon' on silk strands carried by the wind, this is a characteristic of young spiders and not the large adults.

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The invasive joro spider has been slowly spreading through the Smokies, and we need your help to track its whereabouts.

This year, sightings have been confirmed in Georgia, Tennessee, Alabama, and the Carolinas. The Great Smoky Mountains National Park is actively seeking public assistance to map the spiders' distribution. Visitors are encouraged to photograph and report any Joro spiders encountered through the iNaturalist app or by emailing UTKJoroProject@utk.edu.

Researchers emphasize that disturbing these spiders, especially within national parks where it is illegal, is unnecessary. "We also don't know what they are actually doing to our native orb-weavers," stated one researcher, highlighting that this is an area of ongoing study. Outside of parks, while killing them may not be illegal, it is not encouraged. The spiders serve as natural pest control and have not been observed to harm crops or trees. Furthermore, studies indicate they are unlikely to bite humans.

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We also don't know what they are actually doing to our native orb-weavers.